Brown, W.C.

Conrad, P.A.

Grab, D.J.

Iams, K.P.

Nayar, A.

Ole-MoiYoi, O.K.

Sugimoto, C.

CGSpace (CGIAR)

  Protein kinase activation in Theileria-infected cellsO.K. ole-MOIYOI, K. JAMS, A. NAYAR, W.C. BROWN, C. SUGIMOTO, D.J. GRAB and P.CONRADInternational Laboratory for Research on Animal DiseasesP O Box 30709, Nairobi, KenyaProtein kinase activation in Theileria-infected cellsConclusionsReferencesTheileria parva, a tick-transmitted protozoan parasite, is the causative agent of theilerosis, anoften fatal lymphoproliferative disease of livestock in East and Central Africa. The relatedparasites T. annulata and T. sergenti, cause similar diseases in the Middle East/India and theFar East, respectively. Although T. parva sporozoites may enter a variety of bovine cell types,they appear to be able to survive only in subpopulations of lymphocytes in which the parasitedifferentiates into a multinucleate schizont.1 Theileria schizonts are unique among protozoanparasites in that they induce lymphoblastogenesis and clonal expansion of quiescent targetcells. Regardless of pre-infection phenotype, the Theileria-infected cells acquire some surfaceantigens characteristic of proliferating bovine T cells.14 Since such cells are immortalized andcan easily be propagated in vitro, exhibit cellular pleomorphism and appear to acquire avariety of other alterations in surface phenotype,14 Theileria-infected cells have beenconsidered transformed. However, such terminology has been considered misleading since itimplied an oncogenic aetiology and since the infection is curable with administration ofappropriate antibiotics.Protein kinase activation in Theileria-infected cellsAmple evidence has been presented to implicate phosphorylation/dephosphorylation in themodulation of a large number of processes vital to the life of a cell. Among these are cellulardifferentiation, signal transduction and cellular proliferation.2-9 Cells can proliferate in responseto external signals as well as to intracellular events. Membrane receptors for severalpolypeptide hormones and growth factors have been shown to have endogenous tyrosine-specific protein kinase activity.8-11 Upon receptor engagement by ligand, activation of thereceptor kinase occurs, which initiates a series of modifications of specific target molecules,which are thought to constitute intracellular pathways for cellular growth (for review, see 8).Under normal circumstances, when a signal for cell growth ceases, homeostatic regulationensures inactivation of important molecules or the reversion of their levels to those obtained atquiescence. It is thus envisaged that uncontrolled cellular growth could occur if importantmolecules regulating cellular proliferation are constitutively produced or if because of structuralalterations, such molecules cease to be responsive to physiological control.The important roles played by protein kinases in growth of cells stimulated us to determine ifany differences existed between the activities of these enzymes in cloned bovine lymphocytesbefore and after infection with Theileria sporozoites. Supernatant and particulate fractions3(100,000 × g) prepared from IL-2 maintained, con A stimulated or normal peripheral bloodlymophocytes (PBL) were used as control for those from Theileria-infected cells. Mostenzymatic activity was in the 100,000 × g particular fractions and was capable ofphosphorylating both endogenous and exogenous substrates.Analysis of target amino acids residues13 and kinase co-factor requirements showed that theTheileria-associated kinase(s) were cyclic nucleotide independent, Ca++ calmodulin insensitiveand phosphorylated serine/threonine, rather than tyrosine, residues on endogenous proteinsubstrates. Among a large number of exogenous substrates examined, phosvitin, glycogensynthase and a wide variety of casein variants were the best substrates.The susceptibility of the Theileria-associated kinases to inhibition by glycosaminoglycans, 2,3-bisphosphoglycerate, pyridoxal 5'-phosphate and to stimulation by polyamines suggests thatthe dominant protein kinase activity in Theileria-infected cells is casein kinase II-like.6,7Furthermore, employing anti-bovine casein kinase II antibody,5 we have shown that theTheileria-infected cells have markedly increased amounts of casein kinase II antigen. Also theenzymatic activity is susceptible to partial inhibition by this antibody. Interestingly enough, inaddition to a /a1 and b subunits of the bovine casein kinase II, 5,17,18 we also see stronglyreacting antigens in the Mr range of 15-20 kDa. The latter have only been seen so far inTheileria-infected cells. The latter findings are in agreement with our finding a casein kinase II-like enzymatic activity in purified Theileria-macroschizont preparations.19 Current efforts aredirected at structural and functional characterization of the parasite enzyme.Conclusions(1) Our findings of substantial increases of casein kinase II-like enzymatic activity, as well asantigen, in Theileria-infected cells suggest a possible role for this enzyme in Theileria-inducedcellular proliferation. This suggestion is supported by recent findings showing:(a) Brisk activation of casein kinase II in response to hormonal stimulation of cellsin vitro.17(b) Elevation of casein kinase II activity and antigen in differentiating cells.18(c) Significant structural homologies between casein kinase II from varioussources and the products of the cell cycle controlling genes in yeast and otherspecies.12,15,16(2) Induction of uncontrolled cellular proliferation by an intracellular parasite may thus obviatethe need to invoke exogenous factors. The Theileria schizont may activate a pathway that thecell engages in response to normal growth signals. Uncontrolled growth may thus occur ifTheileria drives the lymphocytes to constitutively produce normal growth signal-transducingmolecules or, alternatively, if Theileria-derived analogs of molecular constitutents ofintracellular pathways for growth may not be susceptible to modulation by host-cell elements.References1. BALDWIN, C.L., S.J. BLACK, W.C. BROWN, P.A. CONRAD, B.M. GODDEERIS, S.W.KINUTHIA, P.A. LALOR, N.D. MACHUGH, W.I. MORRISON, S.P. MORZARIA, J. NAESSENSand J. NEWSON. 1988. Infect. Immun. 56: 462-467.2. BISHOP, J.M. 1985. Cell 42: 23-38.3. BROWN, W.C. and D.J. GRAB. 1985. J. Immunol. 133: 3184-3189.4. COOPER, J.A., B.M. SEFTON and T. HUNTER. 1983. Methods Enzymol. 99: 387-402.5. DAHMUS, G.K., C.V.C. CLAIBORNE, D.L. BRUTLAG and M.E. DAHMUS. 1984. J. Biol.Chem. 259: 9001-9006.6. HATHAWAY, G.M. and J.A. TRAUGH. 1982. Cun. Topics Cell. Regul. 21: 101-127.7. HATHAWAY, G.M. and J.A. TRAUGH. 1984. J. Biol. Chem. 259: 7011-7015.8. HELDIN, C-H. and B. WESTERMARK. 1984. Cell 37: 9-20.9. HUNTER, T. and J.A. COOPER. 1985. Ann. Rev. Biochem. 54: 897-930.10. JACOBS, S., F.C. KULL Jr, H.S. EARP, M.E. SVOBODA, J.J. VAN WYK and P.CUATRECASAS. 1983. J. Biol. Chem. 258: 9582-9584.11. KASUGA, M., Y. ZICK, D.L. BLITHE, F.A. KARLSSON, H.U. HARING and C.R. KAHN.1982. J. Biol. Chem. 257: 9891-9894.12. LORINCZ, A.T. and S.I. REED. 1984. Nature 307: 183-185.13. MARTENSEN, T.M. 1984. Methods Enzymol. 107: 3-23.14. NAESSENS, J., J. NEWSON, A. BENSAID, A.J. TEALE, J.G. MAGONDU and S.J.BLACK. 1985. J. Immunol. 135: 4183-4188.15. REED, S.I., J.A. HADWINGER and A.T. LORINCZ. 1985. Proc. Natl. Acad. Sci. USA 82:4055-4059.16. SAXENA, A., R. PADMANABHA and C.V.C. GLOVER. 1987. Mol. Cell. Biol. 7: 3409-3417.17. SOMMERCORN, J. and E.G. KREBS. 1987. J. Biol. Chem. 262: 3839-3843.18. SOMMERCORN, J., J.A. MULLIGAN, F.J. LOZEMAN and E.G. KREBS. 1987. Proc. Natl.Acad. Sci. USA 84: 8834-8838.19. SUGIMOTO, C., P.A. CONRAD, S. ITO, W.C. BROWN and D.J. GRAB. In press. ActaTrop.  

Protein kinase activation in theileria-infected cells

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Protein kinase activation in theileria-infected cells

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